In certain situations, such as the use of a solar panel, it is desirable to maintain equipment at a particular angle relative to a light source, such as the sun. In the specific case of a solar panel, such apparatus may be used to increase the solar energy received by the panel for the length of the day, from when the sun rises in the east until it sets in the west. The prior art has addressed this issue, including solutions making use of actuators following either a specific algorithm from a data processing unit, or acting upon information from light sensors processed by a data processing unit. These actuators require an external power source to supply the motive force for the actuators. Using known solutions, the essentially mechanical operation is controlled by complicated and possibly fragile and expensive computing units. Moreover, the prior art systems require possibly vulnerable connections to external power sources.
For example, U.S. Pat. No. 5,317,145 to Corio, titled, “Radiation Source Detector And Tracker Control having a Shade Pole and Radiation Responsive Surface in the Shape of Narrow Bands” describes a tracker controller system in which a pair of photo-resistive cadmium sulfide sensors mounted in the shadow of a shade pole generate a voltage signal proportional to their resistive values which signal is delivered to a comparator circuit that causes a tracker driver to operate when the voltage signal falls outside of a voltage window established by the comparator circuit.
It will be noted that Corio's system uses resistive cadmium sulfide sensors to detect light. These sensors are resistive elements which do not produce any power. Indeed Corio's system requires an external power supply to power its drivers.
U.S. Pat. No. 4,225,781 to Hammons, titled, “Solar Tracking Apparatus” describes an invention that relates to a solar tracking device which tracks the position of the sun using paired, partially-shaded photocells. Auxiliary photocells are used for initial acquisition of the sun and for the suppression of false tracking when the sun is obscured by the clouds.
It will be noted that although Hammons's system uses photocells, these are used as light sensors to detect the direction of the light source and are not of a size suitable to power the electric motors used for alignment. Again, an external power supply is required for Hammon's system to operate.
It will be appreciated that solar energy is often harvested in environments where external energy sources are unavailable. There is therefore a need for a system that accurately can move an apparatus to maintain a specific optimum angle relative to the sun without the use of microprocessors or external power sources. The embodiments disclosed herein address this need.
Further, in cases where the solar panel comprises photovoltaic cells for the production of electricity from solar power, a large portion of the cost of the system is dependent on the surface area of the active area covered by the photovoltaic cells. In general, when discussing such systems, reference is made to their efficiency in terms of cost-per-watt. Reducing the amount of photovoltaic cell material while maintaining the same wattage output is desirable. The prior art has addressed this issue and various solar concentrating methods have been devised, including those using lenses and parabolic or other curved mirrors to concentrate solar energy. Using known solutions, the solar energy may be concentrated, but the concentrating mechanisms themselves can become prohibitively expensive.
In addition, although greater solar energy concentrated on a smaller photvoltaic panel will provide greater photovoltaic output, much heat is lost in the concentrated solar flux and as a byproduct of the photovoltaic conversion. Furthermore, the heating of the photovoltaic cells will itself lead to a loss of efficiency as the photovoltaic cell material heats beyond its most efficient operating temperature. This may also lead to permanent degradation of the photovoltaic cell material itself over time.
It will be appreciated that there is therefore a need for a cost-effective system that can concentrate solar radiation onto photovoltaic cells and also cool such cells when the concentrated power overheats them. The embodiments disclosed herein address this need.